Storage systems commonly store data by exposing logical volumes to users. Various algorithms for managing volumes are known in the art. For example, Rodeh describes file-system algorithms based on B-trees, in “B-trees, Shadowing, and Clones,” ACM Transactions on Storage, volume 3, no. 4, February, 2008, which is incorporated herein by reference. Rodeh et al. describe a Linux file system based on B-trees, in “BTRFS: The Linux B-Tree Filesystem,” ACM Transactions on Storage, volume 9, no. 3, August, 2013, which is incorporated herein by reference.